This invention relates generally to surgical devices, and more particularly to catheters, dilators and other devices for establishing, restoring or enlarging lumens in the body, especially in the intestines and esophagus.
A variety of body lumens are subject to undesired strictures or narrow regions. For example, blood vessels can be blocked or narrowed by atherosclerosis, while esophageal strictures can arise from individual anatomical differences, or from diseases such as connective tissue disorder. Procedures for dilating or enlarging such strictures or narrowed regions often entail the use of a balloon dilation catheter. Such catheters include a deflated balloon which can be positioned across a particular stricture or narrowed region, and which is then inflated with a fluid in order to widen the lumen without trauma to the wall of the lumen.
A variety of balloon catheters and dilators are known which include a balloon attached to the distal end of a catheter tube or shaft, and which also include a stainless steel or nitinol wire stiffener extending through the catheter shaft and balloon. Balloons for dilating esophageal, pyloric, or colonic strictures can be made of a semi- or non-compliant material that permits sufficient expansile force to dilate the stricture. Non-compliant materials, such as polyethylene terephthalate (PET), are preferred over semi-compliant or compliant materials because they are much less prone to xe2x80x9cdog boningxe2x80x9d, a situation in which the resistance of the stricture forces the fluid in the balloon to either side, therefore providing comparatively less radial or expansile force than would a standard non-compliant balloon.
While dilation of stenoses in blood vessels is usually performed as a one step procedure, there is often a clinical advantage in being able to dilate esophageal and other gastrointestinal strictures using a series of progressively larger balloons so as to avoid tearing or perforation of the luminal wall. The disadvantage of sequentially introducing larger balloons is that multiple introductions increase risk to the patient and prolongs the procedure. One factor determining the length of the procedure is the difficulty in being able to precisely position and reposition the balloon at the stricture. Additionally, patient discomfort is naturally a concern when multiple catheter introductions are required. What is needed is a dilation balloon that can efficiently and effectively perform staged dilation of a stricture while minimizing risk and discomfort to the patient.
The foregoing problems are solved and a technical advance is achieved in an illustrative dilation balloon catheter comprising a single non-compliant balloon, made of polyethylene terephthalate (PET) or another suitable material, that is formed, such as over a mold, to include a plurality of longitudinal sections, each having a different diameter at the center of the section. The balloon can be attached to the distal end of a catheter made of a polymer, such as polyurethane, using a bonding means such as a UV adhesive. In one embodiment used in conjunction with an endoscope to dilate esophageal, colonic, and pyloric strictures, the dilation balloon comprises three sections with the distal section having the smallest diameter. A wire guide, e.g., of a nitinol (NiTi) alloy, can extend through the lumen of the catheter, the balloon, and extend distally, encased in a protective polymer jacket, to aid in cannulation of the stricture.
To cannulate a stricture of a body lumen such as the esophagus, the balloon portion is advanced from the endoscope and the stricture is dilated using the distal (smallest) section. The balloon is usually deflated, then the second, intermediate section, which is about 2 mm larger that the first, is advanced over the stricture and inflated. Finally, the proximal section, which is yet another 2 mm larger, can be used to make a third dilation of the stricture, if desired, before the balloon catheter is removed from the patient. This staged series of inflation helps avoid tearing or perforating of the particular body lumen being dilated, while the single balloon allows a single introduction into the patient for the procedure, rather than requiring three separate introductions of different-sized balloons. In addition, the single balloon can be attached to a smaller diameter catheter, since it is does not have to be multi-lumen, an important advantage when being used in endoscopy.
In one aspect of the invention, the central portion of each balloon section is depressed to form a waist that helps the balloon to center itself over the stricture. This waist, normally 2-6 mm narrower than the adjacent portions of the section, can be configured to include an abrupt change in diameter, creating somewhat of a dumbbell-shaped balloon section, or it may be more gradual in transition. In an illustrative embodiment of a three section balloon, the adjacent portions of the intermediate section are basically shared with the distal adjacent portion of proximal section and the proximal adjacent portion of the distal section, respectively. The number of sections is determined by the number of different central portions or waists of the balloon, rather than the number of adjacent portions, which are often going to be one greater in number than the central portions.
In another aspect of the invention, the longitudinal positions of the different balloon sections can be marked with indicia that can be observed under fluoroscopic imaging and/or via the endoscope. The indicia can be imprinted on, or incorporated into the wire guide that extends through the balloon, using ink, bands, or other means. Additionally, the indicia can be directly printed on, or applied to the balloon surface (e.g., using thin radiopaque foil). The indicia, which preferably marks the center of the balloon section, can be different for each balloon section, or it can be the same.